In recent years, mobile communication services have expanded and increased in popularity around the world. Many advanced networks offer various wireless mobile communication service for voice calls, mobile messaging services (e.g. text and/or multimedia) and data communications. The data services, for example, enable surfing the world wide web via a browser on a mobile station. Further, more and more applications on a mobile station require information identifying location of the mobile station.
There are several existing technologies used for determining a mobile station's position or location. One existing technology employs a Global Positioning System (GPS) installed in a mobile station for determining its location. Another existing technology relies on a backend positioning server on a network to determine location of a mobile station and provides location related information. For example, WiFi and cellular base station based (e.g., cellular identification based) positioning technologies rely on such a backend positioning server to determine location of a mobile station. Both WiFi and cellular base station based technologies are network based positioning techniques since location of a mobile station is determined and provided by a network element (e.g., a positioning server on a network). On the other hand, a mobile station equipped with a standalone GPS does not require the backend positioning server on the network to determine its location. Further, in many mobile applications, these existing technologies can be used in a hybrid fashion to determine location of a mobile station in the fastest and cheapest way (e.g., any one of WiFi based, cellular base station based, or GPS based technology, or any combination thereof). For example, a weather forecast mobile application may only desire a coarse location (e.g., zip code, or city level), making the cellular base station based technology the best fit because it is fastest. A people-tracking application may require a hybrid approach for providing its location based service; for example, when indoors, the WiFi based technology can be used for determining a precise location of the mobile station; and when outdoors, the GPS based approach can be used for determining its location.
As more and more mobile applications rely on acquiring information about location of a mobile station via a hybrid of network based positioning (e.g., using a backend positioning server) and device based positioning (e.g., using a standalone GPS) technologies, there is a growing need for obtaining location information of a mobile station for use by a mobile application while a voice call is in progress on the mobile station. However, some mobile communication or traffic networks, such as certain Third Generation (3G) and earlier Code Division Multiple Access (CDMA) type networks, do not support simultaneous voice and data communications to and from the same mobile station. In such a CDMA type network, if a mobile station is not equipped with GPS or is unable to use its installed GPS, obtaining location information for a mobile application running on the mobile station from a backend positioning server on the network, while a user of the mobile station is on a voice call, is not permitted because both voice and data communications with the mobile station cannot be simultaneously supported, except under certain circumstances, for example, E911 service.
For mobile stations without GPS capability, location based services can be provided by using two types of existing technologies: control plane based technologies and user plane based technologies. The control plane based technologies often refer to technologies that use control channels or air links to the mobile communication network for obtaining location information of a mobile station from a positioning server on a network. On the other hand, the user plane based technologies refer to technologies that use traffic channels or air links to the mobile communication network for obtaining location information of a mobile station from a positioning server on a network That is, in the control plane based technologies the mobile station uses the control channels (or dedicated control channels) of the mobile communication network for signaling to initiate a request for location information of the mobile station and receive the determined location information of the mobile station from the positioning server on the network. In the user plane based technologies, however, the mobile station uses traffic channels (including IP transport bearer) for signaling to initiate a request for location information of the mobile station and receive the determined location information of the mobile station from the positioning server on the network. Thus, in the user plane based technologies, the request and the determined location information are treated as user traffic data.
For example, in a CDMA type network, E911 service uses one of the control plane based technologies to determine location of a mobile station when a user of the mobile station dials 911 for an emergency call. That is, while the user is on the emergency call on a voice channel, a dedicated control channel is used to determine the location of the mobile station. However, control plane based technologies have limitations because they use the circuit switched network and the use of control channels becomes too expensive from a carrier's point of view as a growing number of mobile applications providing location based services use the control channels, which are limited system resources. User plane based technologies provide cheaper alternatives, but not without disadvantages. That is, user plane based technologies require use of Internet Protocol (IP) as a transport bearer and often require simultaneous support of voice and data communications during an active voice call on a mobile station. As a result, in a CDMA type network in which simultaneous voice and data communications cannot be supported by design, existing user plane based technologies (e.g., technologies using the IP as the transport bearer) for location based services cannot be effectively used to obtain location information of a mobile station from a positioning server on the CDMA type network while a user of the mobile station is on an active voice call through the CDMA type network.
Hence, there is still a need for an improved or simplified technique for obtaining information identifying location of a mobile station from a positioning server on a network, while a user of the mobile station is on a voice call through a CDMA type network that does not support simultaneous voice and data communications with the mobile station.